KR19990022920A - Brake parts for elastomeric vehicle - Google Patents

Abstract

Automotive brake parts based on ethylene, alpha-olefin, vinyl norbornene elastomeric polymers are brake parts with lower viscosity, faster and more complete cure than diene monomer compounds other than ethylene, alpha-olefin, vinyl norbornene Prepared with higher efficiency. In addition, brake parts based on ethylene, alpha-olefin, vinyl norbornene elastomeric polymers are, for example, ethylene, alpha-olefin, non-conjugated diene elastomers in which dienes are not vinyl norbornene or styrene butadiene. Compared to rubber, it has improved resistance to elevated temperature properties and good thermal aging properties.

Description

Brake parts for elastomeric vehicle

Recent general trends in vehicles, especially automobiles, are becoming smaller in size compared to automobiles that have been commonly used during the last 75 years of the 20th century. Vehicles are also being designed more aerodynamically. Among other things, these two factors generally make the engine portion of a modern vehicle smaller than the engine portion of a past vehicle. Although the engine part is smaller in size, more functions and devices must enter the engine part. In addition, today's smaller engines with higher speed and more torque are now powerful vehicles.

The combination of these factors raises the temperature of the engine portion and under the hood of the vehicle even further. This increased temperature gives additional stress to the parts of the engine section. For example, at latitude north, most parts of the car are exposed to very low ambient temperatures. At these low temperatures, the rubber parts must maintain their original flexibility in order to function correctly.

The engine temperature at start up and after warm up will be substantially the same at most latitudes. Thus, the low temperature performance characteristics for most automotive parts are generally fixed by the most extreme ambient conditions, while the high temperature characteristics are determined by the factors mentioned above and are generally fixed by the operating temperature of the engine.

The engine temperature can reach 120 ° C. and can often reach 140 ° C. or even 150 ° C., when the vehicle is stopped after operation and in the absence of cooling by external air flows experienced during movement operations. . This extreme (high and low) temperature, which must withstand a relatively short period of time, such as a vehicle used every day, or a long period of time over the life of the vehicle, adds additional stress or requirements to all parts of the engine compartment. Elastomer compounds for engine parts must operate at these temperatures and all or most vehicle components must have a service life of 10 years or 200,000 miles or more.

In addition to long service life in extreme temperature conditions, the bottom hood parts are often or always in contact with conventional vehicle fluids such as brake fluid, air conditioner refrigerants, radiator refrigerants and the like. Exposure to high temperatures or curing in hostile environments can be fatal to materials such as elastomeric automotive parts, so parts suppliers and manufacturers perform the same performance under more severe conditions when processed into lower hood parts, or over a wider temperature range. Find materials that can have improved performance. Brake parts are one of the most important under the hood of the vehicle. They are further stressed not only by the high hood bottom temperatures, but also by the fluids to which they are exposed and the pressure of the fluids at rest. The emergence of anti-lock brake systems (ABS), which increase the stress on the elastomeric parts of the brake system for longer periods of time (10 years and 200,000 miles warranty period), further increases the need for improved brake part performance.

In the past, most brake components have been made from compounds based on styrene butadiene rubber (SBR). Most SBR compounds perform relatively well when the engine temperature is in the range of 100 ° C. In vehicles or in automotive simulated environmental tests, their physical properties, both immediately after manufacture and in curing or in hostile environments, generally begin to drop above 100 ° C. These properties include, but are not limited to, tensile strength, elongation at break, tear resistance, compression set and shrinkage (mass loss).

Until recently, due to their high temperature resistance and better chemical resistance to polar fluids and hot water, compounds based on ethylene, alpha-olefins, non-conjugated dienes, elastomeric polymers made parts of most SBR, In particular, it has been replaced by decisive articles such as brake parts. Most of the ethylene, alpha-olefin, non-conjugated dienes, elastomeric polymer compounds currently used are 5-ethylidene-2-norbornene, 1,4-hexadiene, 1,6-octadiene, 5-methyl- And diene monomers selected from the group consisting of 1,4 hexadiene, 3,7-dimethyl-1,6-octadiene or mixtures thereof.

Processability of compounds prepared from such elastomers is moderate to low because no liquid plasticizer is allowed to prepare the compound. In general, most forms of oils or plasticizers added to rubber / elastomeric compounds can be extracted by brake fluid (DOT3, polyethylene glycol ether or DOT 4 borate ester), causing parts to shrink unacceptably This can negatively change the function of this part. Ethylene, alpha-olefin, non-conjugated dienes, elastomeric polymer compounds are generally known to those skilled in the art such as polymers, carbon blacks, processing aids, curing agents, and the like so that the compounds are substantially free of liquid plasticizers and / or oils. Combined with other additives. Thus, the polymers act as plasticizers while the compound is being processed and have a dual role to ensure that the elastic properties are best provided once cured.

The processability of a given polymer or polymer compound is also important for the manufacture of brake parts with respect to the viscosity and general properties of the product. In general, materials that exhibit lower viscosities without the tendency to prematurely cure or scorch at compounding and molding temperatures are preferred. Rubber compounders for brake component processing include materials such as waxes and / or reinforcing materials, antioxidants, antiozonants, curing agents, accelerators and other additives known to those skilled in the art to produce elastomeric compounds used in brake parts. Will be plasticized or chewed with addition. Typically this plasticization, chewing and / or blending or both is carried out in an internal twister such as a roll mill or a Banbury mixer or the like. After compounding, the material was fed to a device capable of metering the compound (often an extruder) and the blended elastomer was added to the forming steel for molding and curing (the piston of the press).

The economics of manufacturing brake components can be improved in various ways. Practical scales in such molding operations may include larger molds with larger presses and more steel (more parts) and / or faster cycle times. Regardless of the method used, the processability of the elastomeric compound can be substantially impacting in these economic parts.

The lower viscosity of the compound may be the same as filling more mold steel faster. Faster part hardening rates reduce molding cycle time and can also lead to other process improvements that can be economical. As explained above, the lower compound viscosity of a given elastomeric polymer will generally be limited by the viscosity of the elastomeric substrate of the compound during the compounding step. In addition, faster and more complete curing can be controlled within limits by the type or amount of curing agent and heat transfer in the mold. However, blenders often have to compromise between higher levels of hardener and early scorch. Early scorch creates incompletely formed steel fill and component defects. In addition, attempts to increase heat transfer can also cause premature scorch, component defects and incomplete mold steel filling.

Thus, it has improved resistance to high temperature cure in hostile environments in formulations, maintains low temperature flexibility, substantially does not shrink when exposed to thermal and / or polar fluids, and is determined by viscosity at high shear and injection temperatures. There is a commercial need for elastomeric materials that can provide brake components having improved cure rates and improved physical and extrusion cure properties, which are determined by improved compound processability and the time until the mold is cured after filling.

Summary of the Invention

Brake parts made from compounds comprising ethylene, alpha-olefins, vinyl norbornene elastomeric polymers include ethylene, alpha-olefins, non-conjugated dienes, where non-conjugated dienes are 5-ethylidene-2-norbornene. , 1,4-hexadiene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, or a mixture thereof)) Compared with the manufactured brake parts, they generally have improved resistance to deterioration of high temperature cure in air or polar solvents, maintain better performance even at low temperatures, and do not shrink when exposed to thermal and polar fluids. .

In addition, brake component components made from ethylene, alpha-olefin, vinyl norbornene elastomeric polymers and compounds based on these elastomeric polymers are lower for the aforementioned ethylene, alpha-olefin, non-conjugated dienes. By exhibiting viscosity, the processability of the compound is improved, the cure rate is faster, and the cure level is improved.

Vehicle brake parts include ethylene, alpha-olefin, vinyl norbornene polymers, wherein compounds made using such polymers have a) a Mooney viscosity of less than 80 (ML (1 + 4) (100 ° C.)). ; b) MH-ML greater than 140 daN.m (determined by Monsanto Oscillating Disc Rheometer (ODR) 2000 at 180 ° C., ± 3 ° arc); c) a cure rate of at least 70 daN.m / min determined under the same conditions by ODR; d) 100% elongation modulus of at least 5 MPa measured on a pad cured at 180 ° C. for 10 minutes; And e) having a compression set ratio of 25% or less as measured by button curing at 180 ° C. for 12 minutes and compressing by 25% for 22 hours at 150 ° C.

These and other features, aspects, and advantages of the present invention will be better understood with reference to the following description, the appended claims, and the accompanying drawings.

Aspects of the present invention generally relate to molded or extruded elastomeric vehicle brake parts. More specifically, the present invention relates to a vehicle brake component using an elastomeric polymer compound that has been shown to have improved processability and improved curing properties. These elastomeric polymers are generally of the ethylene, alpha-olefin, vinyl norbornene type.

1 shows the effect of the promoter on the polymer composition distribution.

Various aspects of the invention relate to a specific group of processed ethylene, alpha-olefin, vinyl norbornene elastomeric polymer products and their use. These products have unique properties that make them very suitable for use in specific applications. Brake parts, brake devices and the like are made of these compounds and are made of ethylene, alpha-olefins, non-conjugated dienes (eg 5-ethylidene-2-norbornene, 1,4-hexadiene, 1,6-octadiene , Elastomeric polymers containing 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, etc.), and transfers such as styrene butadiene rubber (SBR) and compounds derived therefrom Improved resistance to deterioration in hostile environments for brake parts, brake devices, and the like, based on molded and / or extruded parts made from materials used in the present invention. Detailed descriptions of preferred elastomeric polymers used in the manufacture of such brake parts, within the scope of the present invention, preferred methods of making elastomers, and preferred uses of molded or extruded parts are as follows.

Those skilled in the art will recognize that various changes can be made in these preferred embodiments without departing from the scope of the present invention. For example, the properties of the brake components are used to illustrate the features of the elastomeric polymers of the present invention, but the elastomeric polymers have many other uses. What is specified in this specification is intended to illustrate preferred embodiments of the invention and not to limit the invention to these specific embodiments.

The subheadings in the specification are intended to support the scope of the present invention and are not intended to be limiting in any way.

If ethylene, alpha-olefin, non-conjugated dienes include vinyl norbornene as the non-conjugated diene component, the elastomeric polymer portion of the brake component compound may be in a higher curing state (generally comprising dienes other than vinyl norbornene). To achieve the same curing state or at the same diene weight percent of the elastomeric polymer) or generally requires a lower amount of curing agent and improved resistance to compression set and corrosive air and hot brake fluid aging results It has been found to produce a brake part that has been made. In addition, the ethylene, alpha-olefin, vinyl norbornene, elastomeric polymers of certain embodiments of the invention, which are predominantly brake component compounds, are generally non-conjugated, not previously used ethylene, alpha-olefin, vinyl norbornene. Lower amounts of dienes are required to obtain similar properties as compared to brake parts made of elastomeric polymers based on dienes. Relatively small amounts of vinyl norbornene may further improve thermal aging by extending the temperature operating range of the brake components based on certain embodiments of the present invention or by increasing their useful life compared to previously used materials. Can be. This feature allows the use of materials such as those disclosed herein for brake parts at a wider and more realistic range of temperatures due to ambient conditions (typically low temperature requirements) or increased temperatures of the bottom hood and long part service life.

Combining brake component compounds with improved machinability leading to a more viscous, smoother batch, shorter molding cycle times, for example, improving the properties such as a wider operating temperature range and shrinkage while other important features are not reduced. The ability so far has generally been difficult to obtain.

Brake components made based on the elastomeric polymers of the various aspects of the present invention will include components generally known to those skilled in the art. Such components include, but are not limited to, carbon black, processing aids, waxes, antioxidants, accelerators, curing agents, and the like.

Definition of terms and test methods

variable unit Test Methods Mooney viscosity * ML1 + 4, 125 ° C., MU ASTM D 1646 (Elastic polymer content determination) * ethylene % ASTM D 3900 Ethylidene norbornene vinyl norbornene %% FT-IR ¹ FT-IR / NMR Mooney viscosity (compound) ML1 + 4, 100 ° C, MU ASTM D 1646 Mooney relaxation degree (MLR) MU.S ASTM D 1646 Mooney Scorch Time T _s 5, 125 ℃, min ASTM D 1646 Oscillating Disc Rheometer (ODR), MLMHT _s 2T ₉₀ Curing Rate at 180 ° C, ± 3 ° Arc daN.mdaN.m minutes daN.m / minute ASTM D 2084 Tensile strength modulus at 10 ° C and 180 ° C Modulus 100% tensile strength Elongation at break Shore AMPaMPa% ASTM D 2240 ASTM D 412 dieC Hot air Aging hardness change Tension change Elongation change Weight change at 150 ℃ for 70 hours Shore A %%% ASTM D 573 High temperature hardening in brake fluid, hardness change for 7 days at DOT4, 150 ° C Tensile change Elongation change Weight change Shore A %%% ASTM D 471 Compression set, pressure cured at 180 ° C for 12 minutes, 22 hours / 150 ° C / 25% deflection % ASTM D 395 Method B Tear resistance 25 ℃, 50pphm, 100% elongation resistance at 100 hours Ozone resistance at 51 ℃ for 2 hours at low temperature flexible low temperature shrinkage-TR test kN / m crack crack ASTM D 624 dieCASTM D 1149 ASTM D 1053 ASTM D 1329 Loss tangent peak at 1 Hz glass transition temperature ℃ DMTA Dual Cantilever Mode * Fourier conversion of ethylene, alpha-olefin, diene monomer elastomer polymer 1

Brake component elements that can be expected in various aspects of the invention include cups, coupling discs, diaphragm cups, boots, tubing, sealing gaskets, parts of hydraulic or pneumatic controls, o-rings, pistons, valves, valve seats, valves. Guides, and elastomeric polymers mixed with other elastomeric polymer based parts or other materials such as metal, plastic blends known to those skilled in the art.

Ethylene, Alpha-olefin, Vinyl Norbornene, Elastomeric Polymer Components

The ethylene, alpha-olefin, vinyl norbornene, elastomeric polymer component may contain 50 to 90 mole percent, preferably 50 to 70 mole percent, more preferably 50 to 65 mole percent ethylene, based on the total moles of polymer. It contains. The elastomeric polymer comprises 0.2 to 5.0 mol%, preferably 0.2 to 3.0 mol%, more preferably 0.2 to 2.0 mol%, most preferably 0.2 to 0.8 mol% vinyl norbornene. The remainder of the elastomeric polymer is generally supplemented with alpha-olefins selected from the group consisting of propylene, butene-1, hexene-1, 4-methyl-1 pentene, octene-1, decene-1, mixtures thereof and the like. Preferred alpha-olefins are propylene, hexene-1 and octene-1. The alpha-olefins or alpha-olefins are present in the range of 10-50 mol%, preferably 30-50 mol%, more preferably 35-50 mol% in the elastomeric polymer.

The elastomeric polymer generally has a Mooney viscosity ML (1 + 4) (125 ° C.) of 10 to 80, preferably 15 to 60, more preferably 20 to 40. The elastomeric polymer generally has a branching index (BI) (measurement method disclosed below) of 0.1 to 0.7, preferably 0.1 to 0.6, most preferably 0.1 to 0.5. The elastomeric polymer has a M _w GPC-LALLS / M _n , GPC-DRI (hereafter M _w / M _n ) of 3 or more, preferably 4 or more, more preferably 5 or more, most preferably 6 or more. Have

Other brake compound components

The terms phr per 100 parts of rubber and pphep per 100 parts of the elastomeric polymer are considered to be identical herein.

Carbon blacks used to reinforce rubber are generally produced by burning gaseous and / or hydrocarbon feeds and have a particle size of 20-100 nm for regular furnaces or channel blacks or 150-350 nm for thermal blacks. Have The amount in the compound may be 10 to 200 parts (phr) per 100 parts of the elastomeric polymer.

The processing aids used in these compounds may be mixtures of fatty acid esters or calcium fatty acid soaps bound to mineral fillers. These are used to help mix the compound and inject the compound into the mold. The amount used is 0.5 to 5 (phr).

Another type of processing aid may be a low molecular weight polyethylene (copolymer) wax or a paraffin wax. The amount used can be 0.5 to 5 phr.

Antioxidants can be added to improve long term thermal cure, for example, quinolein (TMQ: trimethyl hydroxyquinolein) and imidazole (ZMTI: zinc mercapto toluyl imidazole). The amount used is 0.5 to 5 phr.

Auxiliaries are addition mechanisms such as sulfur, thiuram (TMTDS or DPPT) (typically 0.3 phr) or methacrylate (EDMA or TMPTM) or modified methacrylates and maleimide (HVA) (typically 0.5 to 5 phr) Or those used to improve peroxide crosslink density by transition mechanisms such as 1,2 polybutadiene or alkyl cyanurate (TAC) (typically 0.5 to 5 phr) and mixtures thereof.

Curing agent (s)

To withstand high temperatures, peroxides are used to cure ethylene, alpha-olefins, vinyl norbornene, elastomeric polymers, the most commonly used being butyl peroxy benzene, butyl peroxy-hexane, dicumyl peroxide, butyl Peroxy-valerate, butyl peroxy methyl-cyclohexane or mixtures thereof and the like. Typical amounts range from 1 to 5 phr calculated on the basis of 100% active base. Compounds formulated according to the following methods have the following properties.

a) Mooney viscosity ML (1 + 4) (100 DEG C) of 80 or less, preferably 70 or less, more preferably 60 or less, most preferably 50 or less;

b) a maximum cure state of at least 140 daN.m, preferably at least 170 daN.m, more preferably at least 190 daN.m, most preferably at least 200 daN.m, MH-ML (ODR 180 ± 3 ° arc);

c) a curing rate of at least 70 daN.m / min, preferably at least 80 daN.m / min, more preferably at least 90 daN.m / min, most preferably at least 100 daN.m / min;

d) 100% modulus of at least 5 MPa, preferably at least 7 MPa, more preferably at least 9 MPa, most preferably at least 11 MPa;

e) Compressive curing rate (22 hours at 150 ° C.) of 25% or less, preferably 20% or less, more preferably 15% or less, most preferably 10% or less.

Compound feature

Typical formulations used for brake component applications

ingredient phr (weight) Elastomeric polymer 100 Carbon Black FEF N550 ⁽¹⁾ 65 Polyethylene Wax AC 617 ⁽²⁾ 2 Processing aids Struktol WB 34 ⁽³⁾ One Antioxidant TMQ Plectol H ⁽⁴⁾ 0.6 Dicumyl Peroxide Dicup 40KE ⁽⁵⁾ 6 (1) Cabot corp. (2) Allied Chemical (3) Schill und Seilacher AG (4) Monsanto Co. (5) Her Hercules

Process for preparing ethylene, alpha-olefin, non-conjugated diene, elastomeric polymer component

Ziegler polymerization of suspended double bonds in vinyl norbornene incorporated into the polymer backbone is believed to produce highly branched ethylene, alpha-olefin, non-conjugated diene elastomeric polymers. This branching process is essentially gel-free ethylene, alpha commonly combined with cationic branched ethylene, alpha-olefins, non-conjugated dienes, elastomeric polymers containing, for example, ethylidene norbornene as terpolymer. To produce olefin, non-conjugated diene elastomeric polymers. Synthesis of substantially gel-free ethylene, alpha-olefin, non-conjugated diene elastomeric polymer elastomers including vinyl norbornene is disclosed in published Japanese Patent Nos. 151758 and incorporated herein by reference in accordance with US patent practice; No. 210169.

Preferred embodiments of the aforementioned documents for synthesizing polymers suitable for the present invention are disclosed as follows.

Catalysts used are VOCl ₃ (vanadium oxytrichloride) and VCl ₄ (vanadium tetrachloride), the latter being the preferred catalyst. The promoter is selected from the same mixture of (i) ethyl aluminum sesqui chloride (SESQUI), (ii) diethyl aluminum chloride (DEAC) and (iii) diethyl aluminum chloride and triethyl aluminum (TEAL). As shown in FIG. 1, the choice of promoter affects the distribution of the composition in the polymer. Other anticipated catalysts and promoters are disclosed in two Japanese published patent applications incorporated by reference above. Polymers with a wider composition distribution are expected to provide worse temperature properties. The polymerization is carried out in a tank reactor which is continuously stirred at 20 to 65 ° C. at a residence time of 6 to 15 minutes at a pressure of 7 kg / cm 2. The concentration of vanadium to alkyl is about 1 to 4 to 1 to 10. 0.3-1.5 kg of polymer is produced per gm of catalyst fed to the reactor. The polymer concentration in the hexane solvent is 3 to 7% by weight.

The resulting polymer had the following molecular properties:

The inherent viscosity measured upon falling at 135 ° C. ranges from 0.5 to 2.0 dl / g. The molecular weight distribution (Mw / Mn) is 3 or more. Branching indexes range from 0.1 to 0.6.

For peroxide curing applications, ethylene, alpha-olefin, non-conjugated diene elastomeric polymers containing vinyl norbornene are ethylene, alpha-olefin, non-conjugated diene elastomeric polymers such as ethylidene norbornene terpolymers. Lower amounts of peroxide are required to obtain the same curing state compared to the monomers. When using ethylene, alpha-olefin, vinyl norbornene elastomeric polymers, typically 20-40% lower peroxide consumption can be realized at a constant diene content. The efficiency of vinyl norbornene, which provides a high crosslink density upon peroxide vulcanization, also generally reduces the total amount of diene needed to obtain the same curing state as the ethylidene norbornene polymer. This generally increases the thermal curing performance by lower diene incorporation. Compared with conventional non-conjugated dienes such as ethylidene norbornene or others, a unique combination of improved processability, lower peroxide utilization and increased thermal curing has been found in ethylene, alpha-olefin, vinyl norbornene elastomeric polymers ( Terpolymers or quaternary copolymers).

The relative degree of branching of ethylene, alpha-olefin, non-conjugated diene elastomeric copolymers is determined using the branching index factor. Calculating this factor involves a series of three laboratory measurements of polymer properties in solution (VerStrate, Gary, Ethylene-Propylene Elastomers, Encyclopedia of Polymer Science and Engineering, 6, 2nd edition (1986)). )need. These were measured using (i) weight average molecular weights (Mw, LALLS) measured using gel permeation chromatography (GPC) after acute angle light scattering (LALLS) technique, and (ii) differential refractive index detector (DRI) (with GPC). Weight average molecular weight (M _w , DRI) and viscosity average molecular weight (M _v , DRI), and (iii) intrinsic viscosity (IV) measured upon falling at 135 ° C.

The first two measurements are obtained at GPC using a filtered dilution solution of the polymer in trichloro benzene.

The average branching index is defined as

Where

M _{v, br} is k (IV) ^{1 / a} ,

M _{v, br} is the viscosity average molecular weight of the branched polymer,

a is the Mark-Houwink constant (0.759 for ethylene, alpha-olefin, diene monomer elastomeric polymer when descending at 135 ° C.).

In Equation 1, the branching index is 1.0 for linear polymers, and for branched polymers, the branching degree is defined relative to the linear polymer. At the constant M _n , the (M _w ) _branching (M _w ) is _linear and for branched polymers BI is less than 1.0 and smaller BI values indicate higher branching values. It should be borne in mind that this method only represents relative branches and does not quantify branches as can be determined using direct measurements such as NMR.

Another method of measuring the effect of branching on the degree of branching and molecular weight distribution is to use a Mooney relaxation region (MLR) (ASTM 1646). In certain Mooneys, MLR is sensitive to branching and molecular weight distribution. Polymers that are more branched and / or have a broader molecular weight distribution have higher MLR when compared at the same Mooney viscosity.

The synthesis of ethylene, alpha-olefin, vinyl norbornene elastomeric polymers is carried out in a laboratory plant unit (4 kg / day yield).

Also contemplated are metallocene catalysis of such monomers comprising the use of a compound capable of activating a Group 4 transition metal compound of the invention in an active catalytic state in the process of the invention for preparing the active catalyst. Suitable activators include ionized uncoordinated anion precursors and alumoxane active compounds, both of which are known and disclosed in the art of metallocene catalysis.

In addition, an active, ion-catalyzed composition comprising a cation and a non-coordinating anion of the Group 4 transition metal compound of the present invention is produced in the reaction of a Group 4 transition metal compound with an ionized non-coordinating anion precursor. The active reaction is typically carried out by separation of R ₁ or R ₂ , in any method including protonation, ammonium or carbonium salt ionization, when the anion precursor ionizes the metallocene by metal cation ionization or Lewis acid ionization. Suitable. The decisive features of this activation are the cationization of the Group 4 transition metal compound, and the resulting miscible, noncoordinating or weak coordinating (included in the term noncoordinating) which may be substituted by the copolymerizable monomer of the invention Its ion stabilization by anions. For example, European Patent Application No. 0 277,003, European Patent Application No. 0 277,004, US Patent Application No. 5,198,401, US Patent No. 5,241,025, US Patent No. 5,387,568, WO 91/09882, WO 92 / Reference may be made to 00333, WO 93/11172 and WO 94/03506, which describe the use of uncoordinated anion precursors with Group 4 transition metal catalyst compounds and their use in polymerization processes and heterogeneous catalysts. Disclosed are their supporting means for manufacturing. Activation with alumoxane compounds, typically alkyl alumoxanes, is less defined for their mechanism of action, but it is nevertheless known to use with Group 4 transition metal compound catalysts, for example US Pat. No. 5,096,867 See. Each of these documents is incorporated herein by reference in accordance with US patent practice.

Example 1

Example 1 is an ethylene, propylene and vinyl norbornene elastomeric polymer prepared using a VOCl ₃ catalyst and an ethylaluminum sesquichloride cocatalyst.

Ethylene is present at 51.6 weight percent. Vinyl norbornene is present at 1.7% by weight. The remainder of the terpolymer is supplemented with propylene. The raw material had a Mooney viscosity ML (1 + 4) (125 ° C.) of 21 and a Mooney relaxation MLR of 145, indicating a high degree of branching.

Example 2

Example 2 is polymerized in substantially the same manner as in Example 1, except that VCl ₄ is used as catalyst. The ethylene content is 48.9 weight percent and the vinyl norbornene content is about 1.9 weight percent. Again, the remainder of the elastomeric polymer is supplemented with propylene. In this example, the elastomer has a Mooney viscosity ML (1 + 4) (125 ° C.) of 20 and a Mooney relaxation degree (MLR) of 206. This shows a higher degree of branching compared to Example 1, and generally indicates improved processing during the compounding operation.

Comparative Example 3

Comparative Example 3 is ethylene / propylene / ethylidene norbornene prepared in a conventional Ziegler polymerization reaction. The product is produced in a single reactor without ammonia to promote cationic branching.

Adding some degree of branching improves processability but is not sufficient to gel the polymer. Branching generally plasticizes the rubber and makes filler incorporation and filler dispersion easier. This is particularly important here because the brake component compound is substantially free of oil or liquid plasticizer. The polymer has an ethylene content of 47.5% by weight, an ethylidene norbornene content of 5.1% by weight, and the remainder of the elastomeric polymer is propylene. Mooney viscosity ML (1 + 4) (125 ° C.) is 17 and MLR is 98. As shown in this document, at equivalent molecular weight, the branching using this technique is not sufficient as ethylene, alpha-olefins, vinyl norbornene, elastomers, as indicated by the Mooney Relaxation Test (MLR).

Comparative Example 4

Comparative Example 4 produces a structure as disclosed in US Pat. No. 4,722,971 to Datta-Kresge, which is polymerized with a broad molecular weight distribution and incorporated herein according to US patent practice.

In this particular example, the ethylene content is 48.3 weight percent, the ethylidene norbornene content is 5.0 weight percent and the remainder of the polymer is propylene. Mooney viscosity ML (1 + 4) (125 ° C.) is 26 and MLR is 146.

The polymer obtained yields the same MLR as Example 1 but at lower Mooney viscosity shows lower processability than Examples 1 and 2.

Examples 5-9

Examples 5-9 use the elastomers of Examples 1-4 as well as commercially available ethylene, alpha-olefin, ethylidene norbornene, elastomeric polymers (Vistalon 2504 available from Exxon Chemical Company). I use it. Vistatalon 2504 has an ethylene content of about 50% by weight, an ENB content of about 4-5% by weight, and the balance is propylene. This product has a typical Mooney viscosity ML of 26 (1 + 4) (125 ° C.) and a typical MLR of 70 (see FIG. II). All materials are blended as disclosed in FIG. The five samples are then tested for physical properties including Mooney viscosity, Mooney scorch time, and Oscillating Disc Rheometer (ODR) data. Blending conditions of the compounds of Examples 5-9 are shown in Table II. As shown in Table II, the processability during the compounding steps of Examples 5, 6 and 7 is acceptable and easily peeled off for production in the form of strips needed to be handled smoothly in an open mill and fed to an injection press. The ones of Examples 8 and 9 are generally unacceptable due to the high stiffness of the batch, which makes it difficult for the operator when handling the batch in an open mill, exhibits high bagging, difficult to cut with a knife and not easy to peel off. As shown in the Mooney viscosity of the compound, two compounds (Examples 5 and 6) based on ethylene, alpha-olefins, vinyl norbornene, elastomeric polymers are substantially lower Mooney measured at 100 ° C. Table I, which shows viscosity, is generally interpreted to improve ease of processing in both the compounding step and the step of injecting the material into the mold. Commercially available elastomers as shown in Example 9 have higher order Mooney viscosity sizes that represent much stronger compounds that are difficult to transport or inject.

Curing properties measured by an oscillating disc rheometer (Monsanto ODR 2000E at 180 ° C., ± 3 ° arc) were obtained from ethylene, alpha-olefin, vinyl norbornene elastomeric polymers, as measured by the difference in MH-ML. It shows a high curing state. Crosslink density is more effective for this type of polymer (Table I). The rate of cure measured with the same device initiates the rate of carbon crosslinking formation at carbon via radical species, ethylene, alpha-olefin, ethylidene norbornene, ethylene, alpha-olefin, vinyl novo for elastomeric polymers. Nene demonstrates the advantages of elastomeric polymers (Table I). It is an advantage of rubber compounders to have a high cure rate that increases productivity.

Table III shows the physical properties of the elastomeric compounds measured on a pad defined by ASTM D412 which is cured in a laboratory electric press at 180 ° C. for 10 minutes.

Table III shows that at the same hardness, the modulus of the vinyl norbornene polymer is generally higher than the polymer containing ethylidene norbornene. This is typical of higher hardening conditions, which is very advantageous for applications such as brake cups that must maintain very high pressures during the brake process. The tensile strengths of Examples 5 and 6 are in the range of examples made of ethylidene norbornene because the average molecular weight between these polymers is very identical. The elongation at break also reflects higher crosslinking for ethylene, alpha-olefins, vinyl norbornene, elastomeric polymers. The air aging data shows that Examples 5 and 6 generally have no weight loss after air aging, which may be substituted by copolymerizable monomers containing two vinyl norbornene, among others. This is an important factor in considering that the brake components often must not shrink during the period of use (this contraction can be a breakdown point of the brake system). Also of note is compression set of materials that exhibit good resistance to compression set and conform well to the specification. At low degrees of compression set, no further improvement can be expected because there are no physical limits (ethylene content and molecular weight) in the polymer composition.

Low temperature properties have been determined by measuring the glass transition temperature of a compound by a method using a dynamic mechanical thermal analyzer (DMTA). The dynamic loss tangent of the rubber cured in double cantilever bending mode with shear vibration of 1 Hz with an amplitude of 0.62 mm increasing from −70 ° C. to + 150 ° C. at 2 ° C./min is measured. The results show that at the same ethylene content, ethylene, alpha-olefin, non-conjugated diene, elastomeric polymers containing ethylidene norbornene are still higher than elastomeric polymers (-44.1 ° C.) containing vinyl norbornene. It has a tan δ peak at (−41.9 ° C.). This indicates that elastomeric polymers containing vinyl norbornene provide the brake parts with lower temperature flexibility, which is required by the manufacturers of these components.

conclusion

The invention may be disclosed in more detail with reference to certain preferred variations thereof, and other variations are possible. For example, although brake parts are illustrated, other uses are also contemplated. Accordingly, the spirit and scope of the appended claims should not be limited to the disclosure of the preferred variations contained herein.

Compound batch Example 5 Example 6 Example 7 Example 8 Example 9 EPDM 100 100 100 100 100 FEF N-550 65 65 65 65 65 PE Wax AC 617 2 2 2 2 2 Struktol WB 34 One One One One One Plectol H 0.5 0.5 0.5 0.5 0.5 Dicup 40KE 6 6 6 6 6 Total PHR 174.5 174.5 174.5 174.5 174.5 Mooney viscosity ML (1 + 4), 100 ° C 52 54 67 83 101 Scotch Ms 125 ℃ Viscosity, MUTs5, Min 1230 or more 2424 2836 3425 3713 ODR ± 3 ° Arc, 180 ° C ML daN.mMH daN.mMH-ML daN.mTs2, min T90, min curing rate daN.m / min 11.5210198.50.653.8108 81821740.754.089 81321240.82.447 12.5147134.50.84.353 15106910.84.235

number Example 5 Example 6 Example 7 Example 8 Example 9 ML 1 + 4, 125 ° C 21 20 17 26 26 Ethylene, wt% 51.6 48.9 47.5 48.3 50 ENB, weight percent Of Of 5.1 5.0 5 VNB, wt% 1.7 1.9 Of Of Of MLR, 125 ℃ 145 206 98 146 70 Mixed BI ^* Time, Ultra Dump Time, Hyper Dump Temperature, Fahrenheit 100300 300 + OK / 300 270 + + easy / smooth 100225300 + OK 100275300-dry / hard / 200320-dry / hard * Carbon black blend

Example 5 Example 6 Example 7 Example 8 Example 9 Physical property, pressure curing at 180 ℃ for 5 minutes Hardness, Shore A100% Modulus, MPa Tensile Strength, MPa Elongation% 739.312.3125 7510.713.5115 73616.4200 713.211.5240 764.116.4250 Air aging, 70 hours at 150 ℃ Tensile change rate% Elongation change rate% Weight change rate% 28231.2 410192.5 5-2521.2 74111.2 410200 Brake fluid curing DOT 4, 7 days 150 ℃ Tensile change rate% Elongation rate change% Volume change rate% 1-20-185.8 0-20-1.76 1632.7 --- 2.8 -3672 Compression hardening 22 hours / 150 ° C / 25% refraction 19 22 28 25 20 Tear resistance Die C, kN / m 3.7 4.2 5.0 - 5.3

Claims (7)

a) up to 80 ML (1 + 4) (100 ° C.); b) MH-ML of 140 daN.m or more (determined by ODR at 180 ° C., ± 3 ° arc); c) a cure rate of at least 70 daN.m / min; d) 100% modulus of 5 MPa or more; And e) Automotive parts made from compounds having a compression set of less than 25% (22 hours at 150 ° C.) and comprising ethylene, alpha-olefin, vinyl norbornene elastomeric polymers. The method of claim 1, The elastomeric polymer is selected from the group consisting of 50 to 90 mol%, preferably 50 to 70 mol%, more preferably 50 to 65 mol%, based on the total moles of the elastomeric polymer; 0.2-5 mol%, preferably 0.2-3 mol%, more preferably 0.2-2.0 mol%, most preferably 0.2-0.8 mol% vinyl norbornene; 10 to 50 mole%, preferably 30 to 50 mole%, more preferably 35 to 50 mole% of alpha-olefins; A vehicle component having a Mooney viscosity of 10 to 80, preferably 15 to 60, more preferably 20 to 40, ML (1 + 4) (125 ° C.), and a branching index of 0.1 to 0.6. The method of claim 2, An automotive part, wherein the alpha-olefin is selected from the group consisting of propylene, butene-1 and octene-1, preferably propylene. The method of claim 3, wherein The compound has a) a Mooney viscosity ML (1 + 4) of 100 or less, preferably 50 or less; b) Cure state MH-ML of at least 190 daN.m / min, preferably at least 200 daN.m / min (determined by ODR at 180 ° C., ± 3 ° daN.m / min.arc); c) curing rate of at least 80 daN.m / min, preferably at least 100 daN.m / min, as determined by ODR; d) 100% modulus of at least 7 MPa, preferably at least 9 MPa; And e) automotive parts having a compression set (22 hours at 150 ° C.) of 15% or less, preferably 10% or less. The method of claim 4, wherein A vehicle part that may be a brake part and may be one of a cup, coupling disc, diaphragm cup, boots, tubing, sealing gasket, o-ring, piston, valve, valve seat, valve guide and combinations thereof. A vehicle brake component compound comprising ethylene, propylene, vinyl norbornene elastomeric polymer, a) 50 to 65 mol% ethylene, 0.2 to 0.8 mol% vinyl norbornene, 35 to 50 mol% propylene in the elastomeric polymer (wherein mol% is the elastic On a total molar basis of the synthetic polymer); b) i) up to 50 ML (1 + 4) (100 ° C.); ii) at least 200 daN.m MH-ML; iii) a cure rate of at least 100 daN.m / min; iv) 100% modulus of at least 9 MPa; And v) compounds having a compression set of 10% or less (22 hours at 150 ° C.). A vehicle comprising a vehicle body and brake parts, a) the brake component comprises ethylene, alpha-olefin, vinyl norbornene elastomeric polymer; i) ethylene is present in the elastomeric polymer at 50 to 65 mole percent; ii) the alpha-olefin is present in the elastomeric polymer at 35 to 50 mole percent; iii) vinyl norbornene is present in the elastomeric polymer at 0.2 to 0.8 mole percent; Wherein mole% is based on the total moles of elastomeric polymer; The elastomeric polymer having a branching index of 0.1 to 0.6 and a Mw / Mn of at least 6 vehicle.